[Histopathological and immunohistochemical study of ovarian polyembryoma]

A case of polyembryoma which is rare in ovarian malignant germ cell tumors was reported. Microscopically, numerous and variable embryoid bodies, surrounded by embryonic hepatoid tissues, trophoblastic cells and multiple elements, were observed. The results of immunohistochemical analysis were: (1) alpha fetoprotein (AFP) was not only shown positive in yolk sac cells among the embryoid bodies, in the endoderm and in the margins of the ectodermal cells, but also in multiple elements in the mucinous matrix. (2) Hepatoid tissues reacted positively to AFP and alpha antitrypsin (AAT) as well as to hCG. (3) By using hCG and human placental lactogen (hPL) as markers it is proven that among trophoblastic cells of the tumor, not only syncytiotrophoblastic cells but also the intermediate cells and the cytotrophoblastic cells could be identified.